CENOZOIC EVOLUTION OF THE SIKHOTE-ALIN RELIEF

Abstract

To ascertain the Cenozoic evolution features of mountain relief we searched the traces of certain development stages, studied the deposits remained in summit mountain zone, and analyzed the correlative deposits, which structure corresponds to different relief morphology. Arial crusts of weathering in different relief types are characteristics of ancient planation surfaces; they are unconformable to present day mountain relief and reflect the early stages of the Sikhote-Alin and East-Manchurian arch development. Crusts of weathering were being developed in conditions of warm and wet climate and growing relief, they have reached their maximal occurrence in the Early-Average Miocene. Oligocene age of crust of weathering in the summit belt of Sikhote-Alin at absolute height over 1300 m was determined on the base of the studying the plant debris, diatoms, spores and pollen in alluvial and lake deposits Accumulation of coarse alluvium in hollows corresponds to epochs of rising. Geomorphologic position of relict crusts of weathering and character of geological sections in depressions of the Southern Far East prove the complex dynamics of relief formation. During the first stage (Pg-N²₁) some weakening of the Sikhote-Alin tectonic contrast took place; its morpostructure combined intermountain depressions, zones of evgemenic type, and mountain rises. The second stage (N³₁-Q) was the epoch of generalization of the structural- tectonic plan of this highland. This process was accompanied by the growth of highlands and by transformation of previous stage crusts of weathering into relict form.